Lennox 4HP18LT User manual

506470-01 Issue 1007
Save these instructions for future reference
INSTALLATION AND MAINTENANCE INSTRUCTIONS
4HP18LT Series
Split System Heat Pump
ManufacturedBy
AlliedAir Enterprises, Inc.
A Lennox International Inc. Company
215 Metropolitan Drive
West Columbia, SC 29170
TABLE OF CONTENTS
INSTALLATION ....................................................2
CONNECTION DIAGRAM....................................4
START-UP..........................................................13
OPERATION ......................................................18
MAINTENANCE .................................................23
*506470-01*
Page 1
The equipment covered in this manual is to be installed by trained and experienced service
and installation technicians. Improper installation, modification, service, or use can cause
electricalshock,fire,explosion,orotherconditionswhichmaycausepersonalinjury,death,
or property damage. Use appropriate safety gear including safety glasses and gloves
when installing this equipment.
WARNING
Installation and servicing of air conditioning equipment
can be hazardous due to internal refrigerant pressure
andlive electricalcomponents.Onlytrainedandqualified
servicepersonnelshouldinstallorservicethisequipment.
Installationandserviceperformedbyunqualified persons
canresultinpropertydamage,personalinjury, or death.
WARNING
Risk of electrical shock. Disconnect all remote power
supplies before installing or servicing any portion of the
system. Failureto disconnect powersuppliescan result
in property damage, personal injury, or death.
WARNING
Sharp metal edges can cause injury. When installing
the unit, use care to avoid sharp edges.
WARNING

506470-01 Issue 1007
INSTALLATION Inspection of Shipment
Upon receipt of equipment, carefully inspect it for possible
shipping damage. If damage is found, it should be noted on
the carrier’s freight bill. Take special care to examine the
unitinsidethecarton ifthe cartonisdamaged.Anyconcealed
damage discovered should be reported to the last carrier
immediately, preferably in writing, and should include a
request for inspection by the carrier’s agent.
If any damages are discovered and reported to the carrier
DO NOT INSTALL THE UNIT, as claim may be denied.
Check the unit rating plate to confirm specifications are
as ordered.
Location of Unit
Outdoor units operate under a wide range of weather
conditions; therefore, multiple factors must be considered
when positioning the unit. The unit must be positioned to
giveadequate clearances forsufficientairflowandservicing.
Refer to Figure 1 for installation clearances.
General
Read this entire instruction manual, as well as the
instructions supplied in separate equipment, before
starting the installation. Observe and follow all
warnings, cautions, instructional labels, and tags.
Failure to comply with these instructions could result
in an unsafe condition and/or premature component
failure.
These instructions are intended as a general guide only for
usebyqualifiedpersonnelanddonotsupersedeanynational
or local codes in any way. The installation must comply with
all provincial, state, and local codes as well as the National
ElectricalCode(U.S.)orCanadianElectricalCode(Canada).
Compliance should be determined prior to installation.
4HP18LT condensing units use R410A which is an ozone-
friendly HFC refrigerant. The unit must be installed with a
matching indoor coil and line set. Afilter drier approved for
use with R410Ais installed in the unit.
IMPORTANT: This product has been designed and
manufactured to meet ENERGY STAR criteria for energy
efficiencywhen matched with appropriate coil components.
However, proper refrigerant charge and proper air flow are
critical to achieve rated capacity and efficiency. Installation
of this product should follow the manufacturer’s refrigerant
chargingandairflowinstructions. Failureto confirmproper
charge and airflow may reduce energy efficiency and
shorten equipment life.
Whenservicing or repairingHVAC components,ensure the
fastenersareappropriatelytightened.Table1 shows torque
values for fasteners.
• Place a sound-absorbing material, such as Isomode
underthe unit ifitwillbe installedinalocation or position
that will transmit sound or vibration to the living area or
adjacentbuildings..
Page 2
Figure 1
Installation Clearances
* A service clearance of 30" must be maintained on
one of the sides adjacent to the control box.
Clearance to one of the other three sides must be
36".Clearance tooneof theremainingtwo sidesmay
be 12" and the final side may be 6".
Aclearance of 24" must be maintained between units.
48" clearance required on top of unit. Maximum soffit
overhang is 36".
36” *
36” *
36”
36”
Table 1
Torque Table
Compressor Bolts 90 in. lbs.
#10 Machine Screws 28 in. lbs.
#8 Machine Screws 16 in. lbs.
Sheet Metal Screws 16 in. lbs.
Service Port Caps 8 ft. lbs.
Stem Caps 8 ft. lbs.
Fastener Torque

506470-01 Issue 1007
Roof Mounting
Install unit at a minimum of 6” above surface of the roof to
avoid ice buildup around the unit. Locate the unit above a
load bearing wall or area of the roof that can adequately
supportthe unit. Consultlocalcodesforrooftopapplications.
• Install the unit high enough above the ground or roof to
allow adequate drainage of defrost water and prevent
ice buildup.
• Inheavy snowareas,donotlocate theunitwheredrifting
snowwill occur. The unitbaseshouldbeelevated above
the depth of average snows.
NOTE: Elevation of the unit may be accomplished by
construction a frame using suitable materials. If a
support frame is constructed, it must not block drain
holes in unit base.
• Wheninstalledin areaswherelowambienttemperatures
exist, locate unit so winter prevailing winds do not blow
directly into outdoor coil.
• Locate unit away from overhanging roof lines which
would allow water or ice to drop on, or in front of, coil or
into unit.
Slab Mounting
When installing a unit at grade level, install on slab high
enough above grade so that water from higher ground will
notcollectaround the unit (See Figure 2). Slabshouldhave
a slope tolerance away from the building of 2° or 2” per 5’.
Thiswill prevent ice from building up under the unit during a
defrost cycle. Refer to following roof mounting section for
barrierconstructionif unit must face prevailingwinterwinds.
If unit coil cannot be mounted away from prevailing winter
winds, a wind barrier should be constructed (See Figure 3).
Size the barrier at least the same height and width as the
outdoor unit. Mount barrier 24” from the sides of the unit in
the direction of the prevailing winds.
Electrical Wiring
Allfieldwiring must be done inaccordancewiththe National
Electrical Code (NEC) recommendations, Canadian
Electrical Code (CEC) and CSA Standards, or local codes,
whereapplicable.
Refer to the furnace or blower coil installation instructions
for additional wiring application diagrams and refer to unit
rating plate for minimum circuit ampacity and maximum
overcurrent protection size.
Page 3
Line voltage is present at all components when unit is
not in operation on units with single pole contactors.
Disconnect all remote electric power supplies before
opening access panel. Unit may have multiple power
supplies. Failure to disconnect all power supplies could
result in personal injury or death.
WARNING
Unit must be grounded in accordance with national and
local codes. Failure to ground unit properly can result in
personal injury or death.
WARNING
Figure 2
Figure 3
Slab Mounting
Discharge Air
Mounting Slab
Ground Level
Building
Structure

506470-01 Issue 1007
1.Installlinevoltagepowersupply tounitfromaproperly
sized disconnect switch. Any excess high voltage field
wiringshould be trimmed or secured away from the low
voltage field wiring.
2. Ground unit at unit disconnect switch or to an earth
ground. To facilitate conduit, a hole is in the bottom of
the control box. Connect conduit to the control box
using a proper conduit fitting. Units are approved for
use only with copper conductors. 24V Class II circuit
connections are made in the low voltage junction box.
Refer to Figure 4 for high voltage field wiring diagram.
Acompleteunitwiring diagram is located inside the unit
control box cover.
3. Install room thermostat on an inside wall that is not
subjecttodrafts, direct sunshine, or other heatsources.
4. Install low voltage wiring from outdoor to indoor unit
andfromthermostatto indoor unit. (SeeWireDiagram
on page 27.)
5. Do not bundle any excess 24V control wire inside
control box. Run control wire through installed wire tie
and tighten wire tie to provide low voltage strain relief
andto maintainseperation of field-installedlow andhigh
voltage circuits.
Refrigerant Piping
If the 4HP18LT unit is being installed with a new indoor coil
and line set, the refrigerant connections should be made as
outlined in this section. If an existing line set and/or indoor
coilwillbeused to complete the system, refer to this section
as well as the section that follows entitled - Flushing
Existing Line Set and Indoor Coil.
If this unit is being matched with an approved line set or
indoor coil which was previously charged with R-22
refrigerant, the line set and coil must be flushed prior to
installation. Ifthe unit is being used with and existingindoor
coilwhich was equipped with a liquid linewhich served asa
meteringdevice (RFCI),theliquid linemustbe replacedprior
to the installation of the 4HP18LT unit.
Field refrigerant piping consists of liquid and suction lines
from the outdoor unit (sweat connections) to the indoor coil
(flare or sweat connections).
Select line set diameters from Table 2 to ensure that oil
returns to the compressor. Size vertical suction riser to
maintain minimum velocity at minimum capacity.
Recommended line length is 50’ or less. If more than 50’
line set is required, contact Technical Services. Table 2
showsthediameters for linesetsup to 100’althoughvertical
lift applications and trapping requirements need to be
reviewed with Technical Services for line sets over 50’.
Installing Refrigerant Line
During the installation of an air conditioning system, it is
important to properly isolate the refrigerant line to prevent
unnecessary vibration. Line set contact with the structure
(wall, ceiling, or floor) may cause objectionable noise when
vibration is translated into sound. As a result, more energy
or vibration can be expected. Close attention to line set
isolation must be observed.
Following are some points to consider when placing and
installing a high-efficiency outdoor unit:
Page 4
Figure 4

506470-01 Issue 1007
Placement
Beaware thatsome localitiesareadoptingsoundordinances
based on how noisy the unit is at the neighbor’s home, not
at the original installation. Install the unit as far as possible
fromthepropertyline. Whenpossible, do not install theunit
directly outside a bedroom window. Glass has a verry high
level of sound transmission. Figure 5 shows how to place
the outdoor unit and line set to reduce line set vibration.
Line Set Isolation
Illustrationson pages6and 7demonstrate procedureswhich
ensure proper refrigerant line set isolation. Figure 6 shows
how to install line sets on horizontal runs. Figure 7 shows
how to make a transition from horizontal to vertical. Figure
8 shows how to install line sets on vertical runs.
Brazing Connection Procedure
1. Cut ends of refrigerant lines square (free from nicks or
dents). Debur the ends. The pipe must remain round; do
not pinch end of line.
2. Before making line set connections, use dry nitrogen to
purge the refrigerant piping. This will help to prevent oxida-
tion and the introduction of moisture into the system.
3. Use silver alloy brazing rods (5% or 6% silver alloy for
copper-to-copper brazing or 45% silver alloy for copper-to-
brass or copper-to-steel brazing) which are rated for use
withR410Arefrigerant.
4. RemovetheSchradercoreassemblies before brazing to
protect them from damage due to extreme heat. Replace
the cores when brazing is complete.
5. Remove light maroon washers from service valves and
shield light maroon stickers to protect them during brazing.
Wrap a wet cloth around the valve body and copper tube
stub to protect it from heat damage.
Page 5
Table 2
Liquid Line
BTUH Line Set Length and Size
12 f t . 25 ft. 50 ft. 75 ft. 100 ft.
3/8 3/8 3/8 3/8 3/8
24,000
3/8 3/8 3/8 3/8
3/8 3/8 3/8 1/2
36,000
3/8 3/8 3/8 1/2
48,000
60,000 1/2
1/2
1/2
Refrigerant Line Set Diameters (in.)
S uction Line
BTUH Line Set Length and Size
12 f t . 25 ft. 50 ft. 75 ft. 100 ft.
3/4 3/4
24,000 7/8
36,000
7/8
7/8
1-1/8
7/8
7/8
1-1/8
48,000
7/87/8
7/8
1-1/8
1-1/8
60,000 1/8 1/8 1-1/8
1-1/8
3/4 3/4
For installations exceeding 50’, contact
Technical Services.
Install unit away
from windows
Two 90° elbows installed in lineset
will reduce lineset vibration
Figure 5
Outside Unit Placement & Installation

506470-01 Issue 1007
6. Brazethelinesettotheservicevalve. Quenchthejoints
with water or a wet cloth to prevent heat damage to the
valve core and opening port. The tube end must stay
bottomed in the fitting during final assembly to ensure
proper seating, sealing, and rigidity.
7. Install the thermal expansion valve which is sold
separately and which is approved for use with R410A
refrigerantin theliquidlineatthe indoorcoil(see Refrigerant
Metering Device on page 9).
Page 6
Whenflushingexistinglinesetand/orindoorcoil,besureto
empty all existing traps. Residual mineral oil can act as an
insulator, preventing proper heat transfer. It can also clog
thethermalexpansionvalve,reducingsystemperformance
andcapacity. Failureto properly flushsystemas explained
intheseinstructions will void warranty.
CAUTION
To hang line set from joist or rafter,
use either metal strapping material
or anchored heavy nylon wire ties.
Strapping Material
(around vapor line only)
8’
8’
Tape or Wire Tie
Strap the vapor line to the joist or rafter
at 8 intervals then strap the liquid line
to the vapor line.
’
Floor Joist or
Roof Rafter
Metal Sleeve
Floor Joist or Roof Rafter
Tape or Wire Tie
Wire Tie
(around vapor line only)
Figure 6
Refrigerant Line Sets: Installing Horizontal Runs

506470-01 Issue 1007
Figure 8
Page 7
Figure 7
Anchored
Heavy Nylon
Wire Tie
Wall
Stud
Metal Sleeve Vapor Line Wrapped
in Armaflex
–
Liquid Line
Wall
Stud
Automotive
Muffler-Type
Hanger
Strap Liquid
Line to Vapor
Line
Metal Sleeve Vapor Line Wrapped
in Armaflex
–
Liquid Line
Strap Liquid
Line to Vapor
Line
Refrigerant Line Sets: Transition from Vertical to Horizontal
Outside Wall
Wood Block
Between Studs
IMPORTANT: Refrigerant
lines must not contact wall.
Vapor Line Liquid Line
Wire Tie
Inside Wall
Strap
Sleeve
Wire Tie
Wire Tie
Strap
Wood Block
Sleeve
Vapor Line Wrapped
with Armaflex
Liquid Line
Caulk
PVC Pipe Fiberglass
Insulation
Outside Wall
IMPORTANT:
Refrigerant
lines must not
contact structure.
Refrigeraant Line Sets: Installing Vertical Runs (new construction shown)
NOTE: Similar installation practices
should be used if line set is to be
installed on exterior of outside wall.

506470-01 Issue 1007
Flushing Existing Line Set and Indoor Coil
This procedure should not be performed on systems
which contain contaminants, such as compressor burn
out.
Required Euipment
The following equipment is needed to flush the existing line
setandindoor coil (See Figure 9). Two cleanR-22recovery
bottles, an oil-less recovery machine with a “pump down”
feature, and two sets of gauges (one for use with R-22 and
one for use with R410A).
Flushing Procedure
IMPORTANT: The line set and/or indoor coil must be
flushed with at least the same amount of refrigerant that
previously charged the system. Check the charge in the
flushing cylinder before flushing the unit.
1. Remove existing R-22 refrigerant using the appropriate
procedure.
Ifthe existingoutdoorunitisnotequipped withshutoffvalves,
or if the unit is not operational AND the existing R-22
refrigerant will be used to flush the system:
Disconnect all power to the existing outdoor unit. Connect
theexistingunit, a clean recovery cylinder, and therecovery
machine according to the instructions provided with the
recovery machine. Remove all R-22 refrigerant
fromtheexistingsystem. Refer tothegaugesaftershutdown
to confirm that the entire system is completely void of
refrigerant. Disconnecttheliquidandsuctionlinesfromthe
existing outdoor unit.
If the existing outdoor unit is equipped with manual shutoff
valves AND new R-22 refrigerant will be used to flush the
system:
Start the existing R-22 refrigerant system in cooling mode
and close the liquid line valve. Pump all the existing R-22
refrigerant back into the outdoor unit.
(It may be necessary to bypass the low pressure switches
to ensure complete refrigerant evacuation.)
When the low side system pressures reach 0 psig, close
the suction line valve. Disconnect all power to the existing
outdoorunit. Refer to the gauges after shutdowntoconfirm
that the valves are not allowing refrigerant to flow back into
thelow side ofthesystem. Disconnect theliquidandsuction
lines from the existing outdoor unit.
2. Remove the existing outdoor unit. Set the new R410A
unit and follow the brazing connection procedure outlined
previously on this page to make line set connections. Do
not install the R410A thermal expansion valve at this
time.
3. Make low voltage and line voltage connections to the
new outdoor unit. Do not turn on power to the unit or
open the outdoor unit service valves at this time.
Page 8
Figure 9
Flushing Connections

506470-01 Issue 1007
4. RemovertheexistingR-22refrigerantflowcontrolorifice
or thermal expansion valve before continuing with flushing
procedures. R-22flowcontroldevicesarenotapprovedfor
usewith R410A refrigerantandmay preventproperflushing.
Use a field-provided fitting to reconnect the lines.
5. Removethe pressure tapvalve cores fromthe 4HP18LT
units service valves. Connect an R-22 cylinder with clean
refrigerant to the suction service valve. Connect the R-22
gauge set to the liquid line valve and connect a recovery
maching with an empty recovery tank to the gauge set.
6. Set the recovery machine for liquid recovery and start
the recovery machine. Open the gauge set valves to allow
therecoverymachinetopullavacuumontheexistingsystem
line set and indoor coil.
7. Invert the cylinder of clean R-22 and open its valve to
allow liquid refrigerant to flow in to the system through the
suction line valve. Allow the refrigerant to pass from the
cylinderandthroughthelineset and the indoor coil before it
enters the recovery machine.
8. Afterallof theliquid refrigeranthas beenrecovered,switch
the recovery machine to vapor recovery so that all of the R-
22vaporisrecovered. Allow the recovery machine to pulla
vacuum on the sytem.
NOTE: Asinglesystemflushshouldremoveallof themineral
oilfromtheexistingrefrigerantlinesandindoorcoil. Asecond
flushingmaybedone(usingclean refrigerant) if insufficient
amounts of mineral oil were removed during the first flush.
After each system flush, allow the recovery machine to
pulla vacuum onthe systemat the endof theprocedure.
9. Close the valve on the inverted R-22 cylinder and the
gauge set valves. Pump the remaining refrigerant out of
the recovery machine and turn the machine off.
10. Use nitrogen to break the vacuum on the refrigerant
linesandindoor coil before removing therecoverymachine,
gauges, and R-22 refrigerant drum. Re-install pressure tap
valve cores into the 4SHP18LT unit’s service valves.
11. Install the fixed orifice (or thermal expansion valve
approvedforusewithR410A refrigerant) in the liquid line at
the indoor coil.
Refrigerant Metering Device
4HP18LT units are designed for use with TXV systems.
Refertotheappropriatefollowingsectionforinformationon
installing the chosen refrigerant metering device.
An R410A system will not operate properly with an R-22
metering device.
Install the refrigerant metering device as shown in Figure
11. Do not twist cap tubes when loosening thesealnutfrom
the orifice housing. Use wrench to back up the distributor.
Expansion Valve Systems
Expansion valves equipped with Chatleff-type fittings are
available from the manufacturer. See Table 3 for proper
TXV for each unit.
To install an expansion valve (See Figure 10 above):
1. Separatethe distributor assembly and remove thepiston
orifice and used teflon seal. Insert nozzle end of the
expansion valve along with a new teflon seal into the
distributorandtighten to20-30 ft. lbs. Use backup wrench
on all wrench flats. Overtightening will crush the teflon
seal and may cause a leak.
2. Attach liquid line portion of distributor assembly along
with new teflon seal to the inlet of the expansion valve.
Tighten to 20 - 30 ft. lbs. Use backup wrench on all wrench
flats. Overtightening will crush the teflon seal and may
cause a leak.
Page 9
Figure 10
Table 3
MODEL PART NUMBER
4HP18LT- 24
4HP18LT - 36
H4TXV01
H4TXV02
4HP18LT - 48, -60 H4TXV03
TXV Data

506470-01 Issue 1007
3. Connect the external equalizer line to the equalizer port
on the suction line and tighten to 8 ft.lbs.
4. Strap the superheat sensing bulb to the suction header.
If installing an expansion valve on an indoor coil that
previouslyused afixedorifice, besuretoremovethe existing
fixedorifice. Failureto remove a fixedorificewheninstalling
an expansion valve to the indoor coil will result in improper
operation and damage to the system.
Manifold Gauge Set
Manifoldguage sets usedwithsystems charged withR410A
refrigerant must be capable of handling the higher system
operating pressures. The gauges should be rated for use
withpressures1-800onthehighside and a low side of 30”
vacuumto250psiwithdampenedspeed to 500 psi. Gauge
hoses must be rated for use at up to 800 psi of pressure
with a 4000 psi burst rating.
Liquid and Suction Line Service Valves
The liquid line and suction line service valves (See Figure
11) and service ports are used for leak teating, evacuation,
charging, and checking charge.
Each valve is equipped with a service port which has a
factory-installedSchradervalve. Aserviceportcap protects
the Schrader valve from contamination and serves as the
primary leak seal.
To Access the Schrader Port:
1. Remove the service port cap with an adjustable wrench.
2. Connect gauge to the service port.
3. When testing is completed, replace service port cap.
Tighten finger tight, then an additional 1/6 turn.
To Open Liquid or Suction Line Service Valve:
Remove stem cap with an adjustable wrench.
Use service wrench with a hex-head extension to back the
stem out counterclockwise as far as it will go. Use a 3/16”
hex head extension for liquid line service valves and a 5/
16” extension for suction line service valves.
Replace the stem cap. Tighten finger tight, then tighten an
additional 1/6 turn.
To Close Liquid or Suction Line Service Valve:
1. Remove the stem cap with an adjustable wrench.
2. Use a service wrench with a hex-head extension to turn
the stem clockwise to seat the valve. Tighten firmly.
3. Replace the stem cap. Tighten finger tight, then tighten
an additional 1/6 turn.
Suction Line (Ball Type) Service Valve
Suctionline(ball type) servicevalvesfunctionthe same way
astheother valves; thedifferenceisintheconstruction (See
Figure 12).
Theball valve is equipped with a service port with a factory-
installed Schrader valve. A service port cap protects the
Schrader valve from contamination and serves as the
primary seal.
Leak Testing
After the line set has been connected to the indoor and
outdoor units, the line set connections and indoor unit must
be checked for leaks.
Page 10
Figure 11